A team of paleontologists has announced in the eLife magazine the discovery of a fossilized heart, so well preserved that it is possible to appreciate its three-dimensional structure . The organ belonged to a fish of the genus Rhacolepis , which lived between 113 and 119 million years ago.
Although it is not the oldest circulatory system that is known – in 2014, paleontologists from different institutions presented that of a 520 million year old arthropod recovered in China that included a tubular heart -, it could be in what refers to vertebrates. Furthermore, according to its discoverers, it has been preserved in such a way that it can even be seen the heart valves –in the image that accompanies these lines, they are indicated with white arrows, in the photo “d” -.
The specimen came to light in the Santana Formation, in northeastern Brazil , and proves that, under certain conditions, soft tissues can persist for millions of years. Usually, these decompose quickly, so that, almost always, only the bones are fossilized, but in the same enclave where this animal has appeared, parts of muscles and the stomach of other prehistoric organisms have been found.
From the remains, the scientists were able to show the 3D structure of the heart using a visualization and image processing system called synchrotron source X-ray tomographic microscopy that allows its internal structure to be laminated and digitally recomposed. Thus, they have even been able to observe the cone and the bulb arteriosus, in the upper part of the organ, where they have found five rows of valves. As they indicate, their disposition is similar to that shown today by other fish , such as the Atlantic tarpon or the tarpons.
The researchers are convinced that new findings like this will be produced, and they point out that the anatomical study of this type of tissue will make it possible to advance in the understanding of the evolution of the heart in vertebrates.
Image: Maldanis et al. (2016)
